The nine-year veteran from Purdue completed 67-of-97 passes for 841 yards, nine touchdowns and two interceptions, giving him a 69.1 completion percentage and a 118.1 passer rating.
In a 45-27 rout of Detroit on Sept. 13, Brees became the first player in NFL history to pass for six touchdowns on Kickoff Weekend.
Other NFC honorees for September were Green Bay cornerback Charles Woodson (defense) and Philadelphia wide receiver/kick returner Sean Jackson (special teams).
Woodson, in his 12th season from Michigan, amassed 10 tackles and two interceptions, and with a 37-yard interception-return for a touchdown in the Packers' 31-24 win over Cincinnati on Sept. 20, he became the first player in franchise history to score on an interception in four straight seasons.
Jackson had 85-yard punt-return touchdown on Sept. 13 against Carolina, the second-longest in team history.